The present invention relates to an improved architecture for a sense amplifier in integrated circuits, to sense small differential signals between ground and a small positive potential.
Increasing attention has been given to sense amplifiers for use in low voltage swing circuits. In low voltage swing circuits, data signals may be carried throughout the circuit as a pair of data signals, a true signal and a complement signal, where the complement signal is a voltage that represent the logical inverse of the true signal. Typically, the true and complement signals are precharged to a predetermined value. During an evaluation phase, the true and complement signals are permitted to carry actual data. One of the signals will evaluate to a different potential than the precharge potential. A sense amplifier for such an application is designed to sense small voltage differentials between the true and complement signals and generate true and complementary output signals in response thereto. By generating output signals in response to the small differentials, the sense amplifier can generate valid output signals without requiring the input data to complete a xe2x80x9cfull railxe2x80x9d transition (e.g. transition fully to VCC or ground). Such a sense amplifier achieves higher throughput and faster speed than circuits that require full rail transitions.
Sense amplifiers are carefully designed to ensure that they include only a minimum number of components sufficient for their operation. A sense amplifier that includes unnecessary components typically has a slower response; it also may consume unnecessary power. Accordingly, there is a continuing need in the art for an LVS sense amplifier having a minimal number of components.
An embodiment of the present invention provides a sense amplifier circuit that includes a pair of differential input terminals and a pair of differential output terminals. Each of a pair of precharge circuits connects a respective one of the differential output terminals to precharge potential and has a clocking input. The precharge circuits maintains the respective differential output terminals at ground in response to a precharge state of a signal at the clocking input. The sense amplifier also may include a pair of evaluation circuits, each connecting a respective one of the differential output terminals to an evaluation potential and coupled to a respective one of the differential input terminals. The evaluation circuits may transition the respective output terminal to an evaluation voltage in response to an evaluation state of a signal at the respective differential input terminal. Further, the sense amplifier may include a pair of clamping circuits, each connecting a respective one of the differential output terminals to ground and maintaining the respective one of the differential output terminal at ground in response to an evaluation voltage at the other of the differential output terminals.